In general, an outboard propulsion unit is secured to watercraft in a manner that allows the unit to pivot relative to the watercraft. Typically, the unit is pivotable through a range of working positions, in which the propeller remains in the water, and through a range of inoperable positions, in which the propeller is raised out of the water.
The first or lower range of pivoting, in which the propeller merely undergoes an adjustment in its angle in the water, may be referred to as the "trim" portion of the available pivotal movement. Typically, the propulsion unit is trimmed to adjust the orientation of the propeller relative to the body of water in which it is operating and/or relative to the transom of the watercraft. In this manner, maximum thrust can be maintained under various operating conditions.
The second or upper range of pivoting, in which the propeller is clear of the water, may be referred to as the "tilt" portion of the upward pivotal movement. The propulsion unit is tilted to avoid damage in very shallow water and during transportation of the boat to and from the water.
The operating parameters associated with moving an outboard propulsion unit through the trim portion of its pivotal movement are distinctly different from the operating parameters associated with moving the unit through the tilt portion of its pivotal movement. For example, trimming may be performed against the thrust of the propulsion unit and may also require finer incremental adjustments in angle than does tilting.
Mechanisms have been proposed and/or are presently available for pivotally mounting outboard propulsion units to watercraft. However, none of these prior art mechanisms satisfactorily addresses the need for the two distinct stages of pivotal movement in a manner that is entirely satisfactory. For example, prior art mechanisms utilize a relatively complicated combination of parts, or a separate operator, such as a hydraulic cylinder, associated with each type of pivotal movement, or a cylinder and pump combination capable of operating at a different speed for each type of pivotal movement. As a result, such mechanisms are relatively expensive and more difficult to operate and maintain. Also, such mechanisms are likely to be relatively heavy and thus, less convenient to handle and transport. As a result of these shortcomings (and others) of prior art mechanisms, a need remains for a device that effectively and efficiently mounts a first object relative to second object and selectively pivots one relative to the other.